At a Mike Long Swimbait seminar he was talking about the Castaic bluegill.
To make it swim better, and sink real slow, bore out a section of the belly in a bullet weight shape and then stick a 3/16 or 1/4 oz. bullet weight into it and then glue it in.
This improves the swimming action greatly and also lets it suspend on structure.
Give it a try.

Oh yeah by the way, I have seen the Mattlures bluegill and it is totally awesome. I can't wait to get one.